/*
 * jdapimin.c
 *
 * Copyright (C) 1994-1995, Thomas G. Lane.
 * This file is part of the Independent JPEG Group's software.
 * For conditions of distribution and use, see the accompanying README file.
 *
 * This file contains application interface code for the decompression half
 * of the JPEG library.  These are the "minimum" API routines that may be
 * needed in either the normal full-decompression case or the
 * transcoding-only case.
 *
 * Most of the routines intended to be called directly by an application
 * are in this file or in jdapistd.c.  But also see jcomapi.c for routines
 * shared by compression and decompression, and jdtrans.c for the transcoding
 * case.
 */

#define JPEG_INTERNALS
#include "jinclude.h"
#include "jpeglib.h"


/*
 * Initialization of a JPEG decompression object.
 * The error manager must already be set up (in case memory manager fails).
 */

GLOBAL void jpeg_create_decompress(j_decompress_ptr cinfo)
{
	int             i;

	/* For debugging purposes, zero the whole master structure.
	 * But error manager pointer is already there, so save and restore it.
	 */
	{
		struct jpeg_error_mgr *err = cinfo->err;
		MEMZERO(cinfo, SIZEOF(struct jpeg_decompress_struct));

		cinfo->err = err;
	}
	cinfo->is_decompressor = TRUE;

	/* Initialize a memory manager instance for this object */
	jinit_memory_mgr((j_common_ptr) cinfo);

	/* Zero out pointers to permanent structures. */
	cinfo->progress = NULL;
	cinfo->src = NULL;

	for(i = 0; i < NUM_QUANT_TBLS; i++)
		cinfo->quant_tbl_ptrs[i] = NULL;

	for(i = 0; i < NUM_HUFF_TBLS; i++)
	{
		cinfo->dc_huff_tbl_ptrs[i] = NULL;
		cinfo->ac_huff_tbl_ptrs[i] = NULL;
	}

	/* Initialize marker processor so application can override methods
	 * for COM, APPn markers before calling jpeg_read_header.
	 */
	jinit_marker_reader(cinfo);

	/* And initialize the overall input controller. */
	jinit_input_controller(cinfo);

	/* OK, I'm ready */
	cinfo->global_state = DSTATE_START;
}


/*
 * Destruction of a JPEG decompression object
 */

GLOBAL void jpeg_destroy_decompress(j_decompress_ptr cinfo)
{
	jpeg_destroy((j_common_ptr) cinfo);	/* use common routine */
}


/*
 * Abort processing of a JPEG decompression operation,
 * but don't destroy the object itself.
 */

GLOBAL void jpeg_abort_decompress(j_decompress_ptr cinfo)
{
	jpeg_abort((j_common_ptr) cinfo);	/* use common routine */
}


/*
 * Install a special processing method for COM or APPn markers.
 */

GLOBAL void jpeg_set_marker_processor(j_decompress_ptr cinfo, int marker_code, jpeg_marker_parser_method routine)
{
	if(marker_code == JPEG_COM)
		cinfo->marker->process_COM = routine;
	else if(marker_code >= JPEG_APP0 && marker_code <= JPEG_APP0 + 15)
		cinfo->marker->process_APPn[marker_code - JPEG_APP0] = routine;
	else
		ERREXIT1(cinfo, JERR_UNKNOWN_MARKER, marker_code);
}


/*
 * Set default decompression parameters.
 */

LOCAL void default_decompress_parms(j_decompress_ptr cinfo)
{
	/* Guess the input colorspace, and set output colorspace accordingly. */
	/* (Wish JPEG committee had provided a real way to specify this...) */
	/* Note application may override our guesses. */
	switch (cinfo->num_components)
	{
		case 1:
			cinfo->jpeg_color_space = JCS_GRAYSCALE;
			cinfo->out_color_space = JCS_GRAYSCALE;
			break;

		case 3:
			if(cinfo->saw_JFIF_marker)
			{
				cinfo->jpeg_color_space = JCS_YCbCr;	/* JFIF implies YCbCr */
			}
			else if(cinfo->saw_Adobe_marker)
			{
				switch (cinfo->Adobe_transform)
				{
					case 0:
						cinfo->jpeg_color_space = JCS_RGB;
						break;
					case 1:
						cinfo->jpeg_color_space = JCS_YCbCr;
						break;
					default:
						WARNMS1(cinfo, JWRN_ADOBE_XFORM, cinfo->Adobe_transform);
						cinfo->jpeg_color_space = JCS_YCbCr;	/* assume it's YCbCr */
						break;
				}
			}
			else
			{
				/* Saw no special markers, try to guess from the component IDs */
				int             cid0 = cinfo->comp_info[0].component_id;
				int             cid1 = cinfo->comp_info[1].component_id;
				int             cid2 = cinfo->comp_info[2].component_id;

				if(cid0 == 1 && cid1 == 2 && cid2 == 3)
					cinfo->jpeg_color_space = JCS_YCbCr;	/* assume JFIF w/out marker */
				else if(cid0 == 82 && cid1 == 71 && cid2 == 66)
					cinfo->jpeg_color_space = JCS_RGB;	/* ASCII 'R', 'G', 'B' */
				else
				{
					TRACEMS3(cinfo, 1, JTRC_UNKNOWN_IDS, cid0, cid1, cid2);
					cinfo->jpeg_color_space = JCS_YCbCr;	/* assume it's YCbCr */
				}
			}
			/* Always guess RGB is proper output colorspace. */
			cinfo->out_color_space = JCS_RGB;
			break;

		case 4:
			if(cinfo->saw_Adobe_marker)
			{
				switch (cinfo->Adobe_transform)
				{
					case 0:
						cinfo->jpeg_color_space = JCS_CMYK;
						break;
					case 2:
						cinfo->jpeg_color_space = JCS_YCCK;
						break;
					default:
						WARNMS1(cinfo, JWRN_ADOBE_XFORM, cinfo->Adobe_transform);
						cinfo->jpeg_color_space = JCS_YCCK;	/* assume it's YCCK */
						break;
				}
			}
			else
			{
				/* No special markers, assume straight CMYK. */
				cinfo->jpeg_color_space = JCS_CMYK;
			}
			cinfo->out_color_space = JCS_CMYK;
			break;

		default:
			cinfo->jpeg_color_space = JCS_UNKNOWN;
			cinfo->out_color_space = JCS_UNKNOWN;
			break;
	}

	/* Set defaults for other decompression parameters. */
	cinfo->scale_num = 1;		/* 1:1 scaling */
	cinfo->scale_denom = 1;
	cinfo->output_gamma = 1.0;
	cinfo->buffered_image = FALSE;
	cinfo->raw_data_out = FALSE;
	cinfo->dct_method = JDCT_DEFAULT;
	cinfo->do_fancy_upsampling = TRUE;
	cinfo->do_block_smoothing = TRUE;
	cinfo->quantize_colors = FALSE;
	/* We set these in case application only sets quantize_colors. */
	cinfo->dither_mode = JDITHER_FS;
#ifdef QUANT_2PASS_SUPPORTED
	cinfo->two_pass_quantize = TRUE;
#else
	cinfo->two_pass_quantize = FALSE;
#endif
	cinfo->desired_number_of_colors = 256;
	cinfo->colormap = NULL;
	/* Initialize for no mode change in buffered-image mode. */
	cinfo->enable_1pass_quant = FALSE;
	cinfo->enable_external_quant = FALSE;
	cinfo->enable_2pass_quant = FALSE;
}


/*
 * Decompression startup: read start of JPEG datastream to see what's there.
 * Need only initialize JPEG object and supply a data source before calling.
 *
 * This routine will read as far as the first SOS marker (ie, actual start of
 * compressed data), and will save all tables and parameters in the JPEG
 * object.  It will also initialize the decompression parameters to default
 * values, and finally return JPEG_HEADER_OK.  On return, the application may
 * adjust the decompression parameters and then call jpeg_start_decompress.
 * (Or, if the application only wanted to determine the image parameters,
 * the data need not be decompressed.  In that case, call jpeg_abort or
 * jpeg_destroy to release any temporary space.)
 * If an abbreviated (tables only) datastream is presented, the routine will
 * return JPEG_HEADER_TABLES_ONLY upon reaching EOI.  The application may then
 * re-use the JPEG object to read the abbreviated image datastream(s).
 * It is unnecessary (but OK) to call jpeg_abort in this case.
 * The JPEG_SUSPENDED return code only occurs if the data source module
 * requests suspension of the decompressor.  In this case the application
 * should load more source data and then re-call jpeg_read_header to resume
 * processing.
 * If a non-suspending data source is used and require_image is TRUE, then the
 * return code need not be inspected since only JPEG_HEADER_OK is possible.
 *
 * This routine is now just a front end to jpeg_consume_input, with some
 * extra error checking.
 */

GLOBAL int jpeg_read_header(j_decompress_ptr cinfo, boolean require_image)
{
	int             retcode;

	if(cinfo->global_state != DSTATE_START && cinfo->global_state != DSTATE_INHEADER)
		ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);

	retcode = jpeg_consume_input(cinfo);

	switch (retcode)
	{
		case JPEG_REACHED_SOS:
			retcode = JPEG_HEADER_OK;
			break;
		case JPEG_REACHED_EOI:
			if(require_image)	/* Complain if application wanted an image */
				ERREXIT(cinfo, JERR_NO_IMAGE);
			/* Reset to start state; it would be safer to require the application to
			 * call jpeg_abort, but we can't change it now for compatibility reasons.
			 * A side effect is to free any temporary memory (there shouldn't be any).
			 */
			jpeg_abort((j_common_ptr) cinfo);	/* sets state = DSTATE_START */
			retcode = JPEG_HEADER_TABLES_ONLY;
			break;
		case JPEG_SUSPENDED:
			/* no work */
			break;
	}

	return retcode;
}


/*
 * Consume data in advance of what the decompressor requires.
 * This can be called at any time once the decompressor object has
 * been created and a data source has been set up.
 *
 * This routine is essentially a state machine that handles a couple
 * of critical state-transition actions, namely initial setup and
 * transition from header scanning to ready-for-start_decompress.
 * All the actual input is done via the input controller's consume_input
 * method.
 */

GLOBAL int jpeg_consume_input(j_decompress_ptr cinfo)
{
	int             retcode = JPEG_SUSPENDED;

	/* NB: every possible DSTATE value should be listed in this switch */
	switch (cinfo->global_state)
	{
		case DSTATE_START:
			/* Start-of-datastream actions: reset appropriate modules */
			(*cinfo->inputctl->reset_input_controller) (cinfo);
			/* Initialize application's data source module */
			(*cinfo->src->init_source) (cinfo);
			cinfo->global_state = DSTATE_INHEADER;
		 /*FALLTHROUGH*/ case DSTATE_INHEADER:
			retcode = (*cinfo->inputctl->consume_input) (cinfo);
			if(retcode == JPEG_REACHED_SOS)
			{					/* Found SOS, prepare to decompress */
				/* Set up default parameters based on header data */
				default_decompress_parms(cinfo);
				/* Set global state: ready for start_decompress */
				cinfo->global_state = DSTATE_READY;
			}
			break;
		case DSTATE_READY:
			/* Can't advance past first SOS until start_decompress is called */
			retcode = JPEG_REACHED_SOS;
			break;
		case DSTATE_PRELOAD:
		case DSTATE_PRESCAN:
		case DSTATE_SCANNING:
		case DSTATE_RAW_OK:
		case DSTATE_BUFIMAGE:
		case DSTATE_BUFPOST:
		case DSTATE_STOPPING:
			retcode = (*cinfo->inputctl->consume_input) (cinfo);
			break;
		default:
			ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
	}
	return retcode;
}


/*
 * Have we finished reading the input file?
 */

GLOBAL          boolean jpeg_input_complete(j_decompress_ptr cinfo)
{
	/* Check for valid jpeg object */
	if(cinfo->global_state < DSTATE_START || cinfo->global_state > DSTATE_STOPPING)
		ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
	return cinfo->inputctl->eoi_reached;
}


/*
 * Is there more than one scan?
 */

GLOBAL          boolean jpeg_has_multiple_scans(j_decompress_ptr cinfo)
{
	/* Only valid after jpeg_read_header completes */
	if(cinfo->global_state < DSTATE_READY || cinfo->global_state > DSTATE_STOPPING)
		ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
	return cinfo->inputctl->has_multiple_scans;
}


/*
 * Finish JPEG decompression.
 *
 * This will normally just verify the file trailer and release temp storage.
 *
 * Returns FALSE if suspended.  The return value need be inspected only if
 * a suspending data source is used.
 */

GLOBAL          boolean jpeg_finish_decompress(j_decompress_ptr cinfo)
{
	if((cinfo->global_state == DSTATE_SCANNING || cinfo->global_state == DSTATE_RAW_OK) && !cinfo->buffered_image)
	{
		/* Terminate final pass of non-buffered mode */
		if(cinfo->output_scanline < cinfo->output_height)
			ERREXIT(cinfo, JERR_TOO_LITTLE_DATA);
		(*cinfo->master->finish_output_pass) (cinfo);
		cinfo->global_state = DSTATE_STOPPING;
	}
	else if(cinfo->global_state == DSTATE_BUFIMAGE)
	{
		/* Finishing after a buffered-image operation */
		cinfo->global_state = DSTATE_STOPPING;
	}
	else if(cinfo->global_state != DSTATE_STOPPING)
	{
		/* STOPPING = repeat call after a suspension, anything else is error */
		ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
	}
	/* Read until EOI */
	while(!cinfo->inputctl->eoi_reached)
	{
		if((*cinfo->inputctl->consume_input) (cinfo) == JPEG_SUSPENDED)
			return FALSE;		/* Suspend, come back later */
	}
	/* Do final cleanup */
	(*cinfo->src->term_source) (cinfo);
	/* We can use jpeg_abort to release memory and reset global_state */
	jpeg_abort((j_common_ptr) cinfo);
	return TRUE;
}
